:root {
  --navy: #111827;
  --ink: #1f2937;
  --muted: #64748b;
  --blue: #156082;
  --blue2: #1c4e88;
  --red: #e82127;
  --orange: #e97132;
  --paper: #f7f8fa;
  --line: #e0e5ec;
  --white: #fff;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Aptos", "Microsoft YaHei", Arial, sans-serif;
  color: var(--ink);
  background: var(--paper);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 14px clamp(18px, 5vw, 72px);
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
}
.brand {
  color: var(--navy);
  text-decoration: none;
  font-weight: 800;
  letter-spacing: 0;
}
.brand span {
  display: block;
  margin-top: 2px;
  color: var(--blue);
  font-size: 12px;
  font-weight: 700;
}
.nav {
  display: flex;
  gap: 18px;
  overflow-x: auto;
  white-space: nowrap;
}
.nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  font-weight: 700;
}
.nav a.active,
.nav a:hover { color: var(--red); }

.hero {
  position: relative;
  min-height: 88vh;
  overflow: hidden;
  background: var(--navy);
}
.hero img {
  width: 100%;
  height: 100%;
  min-height: 88vh;
  object-fit: cover;
  display: block;
}
.hero-shade {
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, rgba(17,24,39,.78), rgba(17,24,39,.36) 45%, rgba(17,24,39,.08));
}
.hero-content {
  position: absolute;
  left: clamp(22px, 7vw, 96px);
  bottom: clamp(44px, 12vh, 118px);
  max-width: 760px;
  color: var(--white);
}
.hero-content p {
  margin: 0 0 14px;
  color: #d8e2ef;
  font-weight: 700;
}
.hero-content h1 {
  margin: 0 0 18px;
  font-size: clamp(44px, 7vw, 86px);
  line-height: .96;
  letter-spacing: 0;
}
.hero-content span { color: #d8e2ef; font-weight: 700; }

.section {
  padding: clamp(54px, 8vw, 96px) clamp(18px, 6vw, 84px);
  max-width: 1280px;
  margin: 0 auto;
}
.section-title {
  max-width: 880px;
  margin-bottom: 30px;
}
.section-title p {
  margin: 0 0 8px;
  color: var(--blue);
  text-transform: uppercase;
  font-size: 12px;
  font-weight: 900;
}
h2 {
  margin: 0;
  color: var(--navy);
  font-size: clamp(30px, 4vw, 50px);
  line-height: 1.05;
  letter-spacing: 0;
}
h3 {
  margin: 0 0 10px;
  color: var(--navy);
  font-size: 20px;
  line-height: 1.2;
}
p { line-height: 1.58; }

.overview-grid,
.feature-grid,
.metric-grid,
.copy-columns,
.controls-layout,
.product-layout {
  display: grid;
  gap: 18px;
}
.overview-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.overview-grid article,
.feature-grid article,
.metric-grid article,
.copy-columns p,
.callout,
.product-layout,
.controls-layout figure {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 24px;
}
.overview-grid strong,
.metric-grid strong {
  color: var(--red);
  font-size: 34px;
  line-height: 1;
}
.overview-grid p,
.feature-grid p,
.metric-grid p,
.copy-columns p { color: var(--muted); }

.metric-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.metric-grid span {
  display: block;
  margin: 10px 0;
  color: var(--navy);
  font-weight: 800;
}
.copy-columns {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: 18px;
}
.feature-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.feature-grid.five { grid-template-columns: repeat(5, minmax(0, 1fr)); }
.callout {
  display: flex;
  align-items: center;
  gap: 22px;
  margin-top: 18px;
}
.callout strong {
  color: var(--red);
  font-size: 48px;
  line-height: 1;
}

.product-layout {
  grid-template-columns: minmax(340px, .95fr) minmax(420px, 1.05fr);
  align-items: start;
  padding: 28px;
  gap: 24px;
}
.lead {
  margin-top: 0;
  color: var(--ink);
  font-size: 18px;
  font-weight: 700;
}
.principle-steps {
  display: grid;
  gap: 10px;
  margin: 22px 0;
}
.principle-steps article {
  display: grid;
  grid-template-columns: 42px 1fr;
  gap: 4px 12px;
  align-items: start;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfdff;
}
.principle-steps span {
  grid-row: span 2;
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border-radius: 50%;
  background: var(--blue);
  color: var(--white);
  font-size: 12px;
  font-weight: 900;
}
.principle-steps strong {
  color: var(--navy);
  font-size: 16px;
}
.principle-steps p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.45;
}
.method-row span {
  border-radius: 999px;
  background: #edf4f8;
  color: var(--blue);
  padding: 10px 14px;
  font-weight: 800;
}
.spec-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}
.spec-grid article {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
}
.spec-grid span {
  display: block;
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
}
.spec-grid strong { color: var(--blue); font-size: 22px; }
.controls-layout img {
  width: 100%;
  max-height: 520px;
  object-fit: contain;
  border-radius: 8px;
  background: #0f172a;
}
.product-media {
  display: grid;
  gap: 10px;
  align-content: start;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #f3f7fb;
}
.media-label {
  margin: 0;
  color: var(--blue);
  font-size: 13px;
  font-weight: 900;
  text-transform: uppercase;
}
.product-video {
  width: 100%;
  aspect-ratio: 480 / 408;
  display: block;
  object-fit: contain;
  border-radius: 8px;
  background: #111827;
}
.test-panel video {
  width: 100%;
  max-height: 520px;
  object-fit: contain;
  border-radius: 8px;
  background: #0f172a;
}
.video-fallback {
  display: none;
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}
.video-fallback.is-visible { display: block; }
.video-fallback a {
  color: var(--blue);
  font-weight: 800;
}

.controls-layout { grid-template-columns: .8fr 1.2fr .8fr; align-items: stretch; }
.controls-layout figure { margin: 0; display: grid; place-items: center; }
.controls-layout figcaption {
  margin-top: 14px;
  color: var(--navy);
  font-weight: 800;
}
.method-row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 18px;
}

.tabs {
  display: flex;
  gap: 10px;
  margin-bottom: 18px;
  overflow-x: auto;
}
.tabs button {
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--white);
  color: var(--muted);
  padding: 10px 16px;
  font: inherit;
  font-weight: 800;
  cursor: pointer;
}
.tabs button.active {
  background: var(--blue);
  color: var(--white);
  border-color: var(--blue);
}
.test-panel {
  display: none;
  grid-template-columns: 1.3fr .7fr;
  gap: 20px;
  align-items: center;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 22px;
}
.test-panel.active { display: grid; }
.test-panel div { padding: 12px; }

.service-section {
  max-width: none;
  background: var(--navy);
  color: #d8e2ef;
}
.service-section .section-title,
.service-section .feature-grid {
  max-width: 1280px;
  margin-left: auto;
  margin-right: auto;
}
.service-section h2,
.service-section h3 { color: var(--white); }
.service-section .section-title p { color: #93c5fd; }
.service-section article {
  background: #1b2636;
  border-color: #3d4c60;
}

.footer {
  padding: 24px clamp(18px, 6vw, 84px);
  color: var(--muted);
  background: var(--white);
  border-top: 1px solid var(--line);
}
.top-button {
  position: fixed;
  right: 18px;
  bottom: 18px;
  width: 42px;
  height: 42px;
  border: 0;
  border-radius: 50%;
  background: var(--red);
  color: var(--white);
  font-size: 20px;
  font-weight: 900;
  cursor: pointer;
  box-shadow: 0 12px 30px rgba(17, 24, 39, .18);
}

@media (max-width: 980px) {
  .site-header { align-items: flex-start; flex-direction: column; gap: 12px; }
  .overview-grid,
  .metric-grid,
  .feature-grid,
  .feature-grid.five,
  .copy-columns,
  .product-layout,
  .controls-layout,
  .test-panel {
    grid-template-columns: 1fr;
  }
  .hero { min-height: 78vh; }
  .hero img { min-height: 78vh; }
  .feature-grid.five { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 560px) {
  .section { padding-left: 16px; padding-right: 16px; }
  .overview-grid article,
  .feature-grid article,
  .metric-grid article,
  .copy-columns p,
  .callout,
  .product-layout,
  .controls-layout figure,
  .test-panel { padding: 18px; }
  .feature-grid.five { grid-template-columns: 1fr; }
  .callout { align-items: flex-start; flex-direction: column; }
  .spec-grid { grid-template-columns: 1fr; }
}